go的interface疑问

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package main

import "fmt"

type Animal interface{
	Talk()
	Eat()
	Name() string
}

type Dog struct{}

func (d Dog) Talk(){
	fmt.Println("汪汪汪")
}
func (d Dog) Eat(){
	fmt.Println("正在吃骨头")
}
func (d Dog) Name() string{
	fmt.Println("名字叫旺财")
	return "旺财"
}
type Pig struct{}

func (p Pig) Talk(){
	fmt.Println("嗯呢嗯")
}
func (p Pig) Eat(){
	fmt.Println("猪正在吃")
}

/*func (p *Pig) Name() string{
	// .\main.go:90:6: cannot use p (type Pig) as type Animal in argument to just:
    // Pig does not implement Animal (Eat method has pointer receiver)
	//指针类型实现了这个接口的方法,不能放入值类型数据
}*/

func (p Pig) Name() string{
	fmt.Println("名字叫旺财猪")
	return "旺财猪"
}
type PuruDongWu interface{
	TaiSheng()
}

func (d Dog) TaiSheng(){
	fmt.Println("狗是胎生的")
}
func testInterface1(){
	var d Dog
	var a Animal
	fmt.Printf("%v, %#v %T, %p \n", a,a,a,&a)
	a = d
	a.Eat()
	a.Talk()
	a.Name()

	var p Pig
	a  = p
	p.Eat()
	fmt.Println("-----------------------1111------------------------------------------------")
	a.Eat()
	a.Talk()
	a.Name()
	fmt.Println("-----------------------------------------------------------------------")
	var d1 *Dog = &Dog{}
	// *(&Dog).Eat()  // a存的是一个值类型的Dog,那么调用a.Eat(), &Dog-->Eat()之后,如果一个变量存储在接口类型的变量中,那么就不能获取这个变量的地址
	a = d1
	a.Eat()
	fmt.Printf("去你大爷的 %v, %#v %T, %p \n",a, a,a,&a)
	//aa := "1"
	a = d  // 指针似乎只能存储结构体对象
	fmt.Printf("去你大爷的aa %v, %#v %T, %p \n",a, a,a,&a)
	var b PuruDongWu
	b = d
	b.TaiSheng()
}

func just(a Animal){
	switch  v := a.(type){
	case Dog:
		fmt.Printf("v is dog,%v\n",v)
	case Pig:
		fmt.Printf("v is pig,%v\n",v)
	default:
		fmt.Println("not support type")
	}
}
func testInterface2(){
	var d Dog
	just(d)

	var p Pig
	just(p)
}


func main() {
	testInterface1()
	// testInterface2()


	
}

输出:

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正在吃骨头
汪汪汪
名字叫旺财
猪正在吃
-----------------------1111------------------------------------------------
猪正在吃
嗯呢嗯
名字叫旺财猪
-----------------------------------------------------------------------
正在吃骨头
去你大爷的 &{}, &main.Dog{} *main.Dog, 0xc0001041e0
去你大爷的aa {}, main.Dog{} main.Dog, 0xc0001041e0
狗是胎生的